With the development of the information society, portable information devices such as phones, computers, and digital cameras have been widely used. There are limitations on weight and volume of a portable information device so that the information device is carried. In particular, the proportion of weight and volume of a battery is high in an information device; thus, the capacity of the battery is limited.
In order to provide a portable information device having a battery with limited capacity that can be used for a long time, it is necessary to use components and devices with less power consumption for the portable information devices. As an example of the display device with less power consumption, a reflective liquid crystal display device is given.
Since in a refractive liquid crystal display device, a backlight is not used and external light is utilized for display, the power consumption of the liquid crystal display device is low. As an example of the reflective liquid crystal display device, a display device in which a reflective electrode is provided with a texture structure formed including a material with a low refractive index and a light-reflecting film formed including a material with a high refractive index is formed thereover has been invented (see Patent Document 1).